Motor fuel composition

ABSTRACT

Motor fuel composition: A. GASOLINE BASE B. ESTERS OF A POLYMETHYLOL COMPOUND AND AN ALIPHATIC MONOCARBOXYLIC ACID HAVING FROM 14-24 CARBON ATOMS.

United States Patent Biasotti et al.

[451 Sept. 23, 1975 MOTOR FUEL COMPOSITION Inventors: Joseph Brian Biasotti; Frederick G.

Oberender, both of Wappingers Falls, NY.

Assignee: Texaco Inc., New York, NY.

Filed: May 18, 1973 Appl. No.: 361,682

US. Cl, 44/58; 44/66 Int. Cl ..C10l l/18 Field of Search 44/58, 66

References Cited UNITED STATES PATENTS 11/1970 Bork 44/66 X OTHER PUBLICATIONS Barnes et al., Lubrication Engineering," Aug. 1957, pp 454458.

Primary ExaminerDelbert E. Gantz Assistant Examinerl. Vaughn Attorney, Agent, or Firm-T. H. Whaley; C. G. Ries; J. J. OLoughlin [57] ABSTRACT 11 Claims, N0 Drawings BACKGROUND OF THE INVENTION I 1. Field of Invention r Internal combustion engines, particularly of the overhead valve design, are subject to a substantial buildup of hard, tenacious deposits on the intake valves of the engine. These deposits seriously interfere'with the operation of the engine. As the deposits levels grows, the

engine exhibits loss of power, rough idling, and, even, valve burning. When the deposits becomes excessive,

portions break off and are drawn into the combustion chamber where instances of mechanical damage to the piston and piston rings caused by same have been observed. i i A 7 ii Considerable work has been conducted to determine the nature and cause of the intake valve deposits. The deposits themselves arecomposed essentially of the byproducts of fuel combustion and lubricating oil deterioration. Analysis of the deposits indicates that'the viscosity index improvers contained in the lubricating oil act as binders for the deposits. Polymethacrylate viscosityindex improvers, as an example,'are one classof materials which appear to contribute substantially to the deposit build-up. i i

An understanding of modern internal combustion" engine operation will indicate how lubricating oil deterioration can contribute to deposits in the fuel intake sys tern. A spark-ignited internal combustion engine contains a reservoir of lubricating oil in the crankcase. When in operation, thepriniary lubrication is effected by the crankcase oil being splashed up on the operating parts of the engine and on the cylinder walls. A portion of the oil,ihowe ver, is pumped under pressure to the upper parts of the engine to lubricate the working parts therein. In an overhead valve engine, a small stream of the oil pumped to the upper sectio'n'of the engine is constantly run down the intake and exhaust valve stems to insure that they are always lubricated in their guides during operation. The oil trickling down the intake valve steam, stem, valve head and around the intake port is pyrolyzed under the temperatures prevailing, resulting in the formation and build-up of intake valve and port deposits.

7 Modern internal combustion engine design'is undergoing important changes to meet stricter standards concerningengine and exhaust gas emissions. A major change in engine design adopted is the feeding of blowby gases from the crankcase zone ofthe engine into the intake air supply to'the carburetor just below the throttle plate, rather thaan venting these gases to the atmo- .sphere as in the past. Theseblow -by gases contain substantial amounts of deposit-forming substances and tend to aggravate the problem of intake valve and port deposits.

2. Description of thePrior' Art t v U.S. Pat.No. 3,502,451 discloses a motor fuel composition for agasoline internal combustion engine con taining a polymer, copolymer or hydrogenated polymer. Specifically, a polymer of a C to C unsaturated hydrocarbon, a copolymer of a C to C unsaturated hydrocarbon, or a hydrogenated polymer or copolymer of a C to C unsaturated hydrocarbon having a molecular. weight in the range of from about 500 to 3 500 'is employed at a concentration from about 0.01 to0.20 volurne percent in the motor fuel compositionfora sparkformation of deposits on'the intake valves and ports of the engine.

. US. Pat. No. 3,574,475 discloses a motor fuel com- A position for a gasoline internal combustion engine containing a polyester of polymerized linoleic acid, i.e.,

dimer or trimer acid to prevent intake valve and port deposits. British Pat. Specification No. 1,180,387 discloses synthetic aircraft turbine oil composition in which the base oil comprises a polyester formed from a polymethylolcompound and a saturated monocarboxylic acid having from 3 to' 10 carbon atoms.

SUMMARY OF THE INVENTION T he motor fuel composition of the invention comprises'a mixture of hydrocarbons in the gasoline boiling range containing a minor amount of an ester of a polymethylol compound and a (C to C aliphatic hydrocarbon monocarboxylic acid having an average molecular weight ranging from about 800 to 2500.

More specifically, the motor fuel composition of the invention comprises a mixture of hydrocarbons boiling from about 80 to 450F. and containing from about 0.015 to about 0.25 weight percent of said prescribed ester of a polymethylol compound and saturated mono carboxylic acid.

SPECIFIC EMBODIMENTS OF THE INVENTION The ester of a polymethylol compound selected from the group consisting of tetramethylolmethane (pentaery-thritol), and polymethylol derivatives of ethane, propane and butane in which the derivative has at least three methylol groups, and a saturated aliphatic hydrocarbon monocarboxylic acid having from about 14 to 24 carbon atoms or a relatively highly saturated mixture of aliphatic hydrocarbon monocarboxylic acids,

which is effective for preventing or reducing intake valve deposits in a-gasoline engine, is prepared by Conventional methods. In general, suitable proportions of the prescribed polymethylol compound and aliphatic monocarboxylic acid are admixed, preferably in a solvent such as an aromatic hydrocarbon, and reacted in the presence of a catalyst, such as HCl, HF, HBr, H 80 and the like. The preparation of these esters is described in US. Pat. Nos. 3,038,859 and 3,121,109.

Specific polymethylol compounds suitable for preparingthe ester include tetramethylotmethane, 1,2,3- trimethylolpropane, 1,1 ,2-trimethylolethane, 1,2,4- trimethylolbutane and the tetra-and higher methylol derivatives of ethane, propane, butane and isobutane.

The preferred acid or mixture of acids for preparing the neutral esters are the saturated aliphatic monocarboxylic acids having from about 14 to 24 carbon atoms. This class includes myristic acid, palmitic acid, stearic acid, nondecylic acid, arachidic acid, and behenic fatty acids. Effective esters, however, can be prepared from mixtures of fatty acids containing a minor portion of unsaturated fatty acids. It is essential that the mixture of fatty acids consist of af least 50 percent of saturated fatty acids. It is preferred however, to employ a mixture of fatty acids that consists of at least percent of saturated fatty acids in the prescribed C to C carbon chain length. It hasbeen established that esters formed from unsaturated fatty acid do not provide the improvementto which this invention is directed.

Eicosadienoic Acid, 7: 9

By far the most preferred esters are the full'y esterified products formed from, aliphatic hydrocarbon monocarboxylic acids or mixturesofrs ame that are essentially 100 percent saturated. And the preferred saturated acids for forming-these esters are those having from 16 to carbon atoms. 1 v 1 Not all of the hydroxyl groups inthe polymethylol compound need be esterified to form effective neutral esters for this invention. It is critical, however, that the average-molecular weight of the ester-bein the range from about 800' to 2500. The preferred molecular weight range for the ester additiveis from about 825v to 1500 with the-particularly preferred range being from about 850 to 1200. It will be understood that minor amounts of lower molecular weight aliphatic monocarboxylic acids, i.e., acids having from 2'12 carbon atoms, may be present in the ester without diminishing the effectiveness of the'ester so long as it meets the critical parameters set out above.

The esters employed in the fuel composition of this invention as well as comparison fuel compositions were prepared form the following mixtures. of fatty acids.

TABLE '1 COMPOSITION OFiAClDS Lower Boiling Acids, 7 Palmitic Acid, 7: Palmitoleic Acid"7z Stearic Acid, 7

Oleic Acid, 7: Linoleic Acid, 7: Eicosanoic Acid, 7:

Eicosatrienoic Acid, 7: Behenic Acid,- 72 Others, 72 Unsaturation, 7:

The description of the preparation of esters effective in the present 'fuel compositions and of ester compositions employed in comparison fuels are set forth in the following examples and the molecular. weight calculated from the acid composition.

EXAMPLE 1 1,281 grams (4.8 m.) ofAcid C and 163.2 grams 1.2 m.) of tetramethylolmeth'ane were dissolved in 400 milliliters of xylene. The mixture was reacted at 210C. for a period of 9.5 hours. The solvent was removed by distillation yielding 1351 grams of the ester product havingan average molecular weight of about 1 136.

EXAMPLE 11 1,104 grams Acid D (3.9 m.) and 174.2 grams (1.3 m.) of trimethylolpropane were dissolved in 400 milliliters of xylene. The mixture was reactedat 210C. for a total of 17 hours. The solvent was then removed by distillation'yielding 1196 grams of the ester product having an average molecular weight of about 923.

EXAMPLE Ill EXAMPLE. 1v

1,030. grams (2.8 m.) ofAcid B and 95.2 grams (0.7 m.) of tetr'amethylolmeth'ane were dissolved in 400 milliliters in xylene. This mixture was reacted at 190C. for. S hours and at 2109C. for an additional 3hours. The solvent was removed;-

distillation yielding 1061 grams of the esterproduct having an average molecular weight of about.l1.44.,i, t i i EXAMPLEV 774.9 grams "2.7 in. ojfiAcid "A and 120.6 grams of trimetlty lolpropane,vvere dissolved in 400 milliliters of xylene. This mixture was reacted at 210C. for 20.5 hours. hes olvent was removed by distillation yielding 834 grams of the ester product having an average molecular weight of about 932. v

U a I EXAMPLE VI 1 f .994 grams 2.7 rh. i f Acid d 120:.6gram s of trimethylolpropane were dissolved 400 milliliters of xylene. This mixturewas'reac'ted at 2l0C.for 12 hours The solvent was removed distillation yielding 1061 grams of the ester product have an average molecular weight of.aboutf8 90. j, l a a The base fuelwhich is employed in the motor fuel composition of the invention comprises a mixture of hydrocarbons boiling in the gasoline boiling range. This base fuel may consist of straight-chain or branchedchain paraffms, cycloparaffins, olefins, and aromatic hydrocarbons or any mixture of these. The base fuel can be ,derived from straight-run inaph'th'a, polymer'gasoline, natural gasolineor. fromcatalytica'lly cracked or thermally cracked hydrocarbons and catalytically reformed stocks and boils in the range about to 450F. The composition and the octane level of the base fuel are not critical. Any conventionalmotoii fuel base may be employed in the practice of this'inventiori. ..l n general, the additiveof the invention is added to the base fuel in a minor amount, ma arhount'effective to prevent .or reduce the formation of intake valve deposits in an internal combustion gasoline engine. The

concentration of the additive in the fuel composition is critical. Amounts below about volumep'ercent are not effective. The broad effective range in volume percent based on the total fuel compositionis from about 0.015 to 0.25 percent. An amount ranging from I about 0.02 to 0.10 volume percent is preferred with the most preferred concentration ranging from' about 0.05 to 0.08volume percent. I l

The fuel composition of the invention may contain any of the additivesnorinally employed in a motor fuel. For example, the base fuel may be blended with an anti-knock compound, such as a tetraalkyl lead compound, including tetraethyl lead, tetrarnethyl lead, tetrabutyl lead, and chemical and physical mixtures thereof, generally in a concentration from about 0.05

to 4.0 cc. per gallon of gasoline. The tetraethyl lead- .The base fuel which was utilized to test the additives of this invention was a premium grade of gasoline .without detergent, corrosion inhibiting, or ISD control additives. This base fuel boiled in the range of about 92 to 373F. and had the following composition with respect tox hydrocarbon type, Research Octane Number (RON) and concentrations of tetraethyl lead (TEL):

Gravity. API 60.9

I TEL. cc/gal. 3.l

RVP. lbs. 8.5

FIA Aromatics 30.0

- Saturates 67.5

Octane number RON 99.2

Gasoline blends were prepared consisting of the above base fuel mixed with specified amounts of the prescribed fuel additive and comparison additives. These gasoline blends, as well as a sample of thebase fuel. were then subjected to the following performance test:

BUICK INDUCTION SYSTEM DEPOSIT TEST This test is conducted using, as a test engine, a 1964 Buick 425 CID V-8 engine equipped with a Positive Crankcase Ventilation (PCV) valve and installed on a dynamometer test stand with auxiliary equipment to control speed and engine temperatures. This test requires approximately 350 gallons of fuel and 4 gallons of lubricant.

Prior to each run, the cylinder heads are completely reconditioned, and reconditioned intake valves in stalled. Inlet valve-to-valve guide clearance is maintained within the manufacturers recommended limits. When blow-by or oil consumption becomes excessive, the engine block is completely overhauled in accordance with the procedures specified in the 1964 Buick Service Manual.

The engine is drained and charged with 4 quarts of new oil and operated on a four-stage, six-hour cycle for a total of 16 cycles or 80 hours, as follows:

in. Hg "Typical values. not controlled.

Upon completion of a run, the cylinder head and valves are removed and the valves visually rated for the extent of deposit build-up on the valve tulip surface. The intake valve deposits are rated according to a merit rating scale running from to l. The rating 10 is a perfectly clean valve. The rating I is applied to an extremely heavily coated valve.

In this test, the base fuel employed is a typical leaded premium gasoline which does not contain detergent of induction system deposit (ISD) modifier additives. Using the base fuel in this test, the typical average intake valve rating is about 6.4.

The results obtained using the fuel composition of the invention as well as comparison fuels are set forth in the following table.

TABLE II BUICK INDUCTION SYSTEM DEPOSIT TEST (ISD) TEST ""Average of two runs In the foregoing Buick Induction System Deposit Test, Runs 2 and 4, conducted employing fuel compositions in which the ester additive was prepared from highly unsaturated fatty acids described as Acid A in Table I, were poorer than the Base Fuel which gave a Value Deposit Rating of 6.4. Runs 3 and 5, conducted employing fuel compositions in which the ester additive was prepared from fatty acids containing about 50.2 percent saturation and described as Acid B, were slightly better than the Base Fuel. Runs 6 and 7, conducted using fuel compositions containing the preferred ester additive of the invention formed from saturated fatty acids, demonstrated outstanding intake valve cleanliness as shown by Value Deposit Ratings of 9.4 for each run. It is apparent on the basis of this data that fuel compositions employing saturated esters provide maximum valve stem deposit control. It is also evident that fuel compositions employing esters prepared from mixtures of acids containing more than 50 percent saturated acids also provide intake valve cleanliness better than base fuel.

We claim: I

1. A motor fuel composition comprising a major amount of a mixture of hydrocarbons in the gasoline boiling range from about 80 to 450F. containing a minor amount effective to reduce intake valve deposits in a gasoline engine of an ester compound formed from a polymethylol alcohol from the group consisting of tetramethylolmethane, and polymethylol derivatives of ethane, propane, and butane in which the derivatives has at least three methylol groups, and an aliphatic hydrocarbon monocarboxylic acid from the group consisting of saturated aliphatic acids having substantially 14 to 24 carbon atoms and mixtures of substantially C H to C aliphatic acids consisting of at least 50 percent of saturated acids. said ester compound having an average moleeular weight ranging from about 825 to I500.

2. A motor fuel composition according to claim 1 containing from about 0.015 to 0.25 volume percent of said ester.

3. A motor fuel composition according to claim 1 in which said ester compound has an average molecular weight ranging from about 850 to 1200.

4. A motor fuel composition according to claim 1 in which said aliphatic hydrocarbon monocarboxylic acid has from about 16 to 20 carbon atoms.

5. A motor fuel composition according to claim 1 in which said monocarboxylic acid comprises a mixture of aliphatic hydrocarbon monocarboxylic acids consisting of at least percent of saturated acids.

6. A motor fuel composition according to claim 1 in which said acid is a saturated aliphatic hydrocarbon monocarboxylic acid.

7. A motor fuel composition according to claim 1 in which said ester is formed from tetramethylolmethane and a saturated aliphatic hydrocarbon monocarboxylic acid having from about 16 to 18 carbon atoms.

8. A motor fuel composition according to claim 1 in which said ester is formed from trimethylolpropane and and aliphatic monocarboxylic acid having from about 16 to 18 carbon atoms.

9. A motor fuel composition according to claim 1 containing from about 0.02 to 0.10 volume percent of said ester.

10. A method for operating an internal combustion gasoline engine which comprises supplying to and burning in said engine a motor fuel composition comprising a major amount of a mixture of hydrocarbons in the gasoline boiling range from about to 45 0F. containing a minor amount effective to reduce intake valve deposits of an ester compound formed from a polymethylol alcohol from the group consisting of tetramethylolmethane, and polymethylol derivatives of ethane, propane, and butane in which the derivative has at least three methylol groups, and an aliphatic hydrocarbon monocarboxylic acid from the group consisting of saturated aliphatic acids having substantially 14 to 24 carbon atoms and mixtures of substantially C to C aliphatic acids consisting of at least 50 percent of saturated acids, said ester compound having an average molecular weight ranging from about 825 to 1500.

11. A method according to claim 10 in which said fuel composition contains from about 0.015 to 0.25

volume percent of said ester. 

1. A MOTOR FUEL COMPOSITION COMPRISING A MAJOR AMOUNT OF A MIXTURE OF HYDROCARBONS IN THE GASOLINE BOILING RANGE FROM ABOUT 80* TO 450*F CONTAINING A MINOR AMOUNT EFFECTIVE TO REDUCE INTAKE VALVE DEPOSITS IN A GASOLINE ENGINE OF AN ESTER COMPOUND FORMED FROM A POLYMETHYLOL ALCOHOL FROM THE GROUP CONSISTING OF TETRAMETHYLOLMETHANE AND POLYMETHYLOL DERIVATIVES OF ETHANE PROPANE AND BUTANE IN WHICH THE DERIVATIVES HAS AT LEAST THREE METHYLOL GROUPS AND AN ALIPHATIC HYDROCARBON MONOCARBOXYLIC ACID FROM THE GROUP CONSISTING OF SATURATED ALIPHATIC ACIDS HAVING SUBSTANTIALLY 14 TO 24 CARBON ATOMS AND MIXTURES OF SUBSTANTIALLY C14 TO C24 ALIPHATIC ACIDS CONSISTING OF AT LEAST 50 PERCENT OF SATURATED ACIDS SAID ESTER COMPOUND HAVING AN AVERAGE MOLECULAR WEIGHT RANGING FROM ABOUT 825 TO
 1500. 2. A motor fuel composition according to claim 1 containing from about 0.015 to 0.25 volume percent of said ester.
 3. A motor fuel composition according to claim 1 in which said ester compound has an average molecular weight ranging from about 850 to
 1200. 4. A motor fuel composition according to claim 1 in which said aliphatic hydrocarbon monocarboxylic acid has from about 16 to 20 carbon atoms.
 5. A motor fuel composition according to claim 1 in which said monocarboxylic acid comprises a mixture of aliphatic hydrocarbon monocarboxylic acids consisting of at least 75 percent of saturated acids.
 6. A motor fuel composition according to claim 1 in which said acid is a saturated aliphatic hydrocarbon monocarboxylic acid.
 7. A motor fuel composition according to claim 1 in which said ester is formed from tetramethylolmethane and a saturated aliphatic hydrocarbon monocarboxylic acid having from about 16 to 18 carbon atoms.
 8. A motor fuel composition according to claim 1 in which said ester is formed from trimethylolpropane and and aliphatic monocarboxylic acid having from about 16 to 18 carbon atoms.
 9. A motor fuel composition according to claim 1 containing from about 0.02 to 0.10 volume percent of said ester.
 10. A method for operating an internal combustion gasoline engine which comprises supplying to and burning in said engine a motor fuel composition comprising a major amount of a mixture of hydrocarbons in the gasoline boiling range from about 80* to 450*F. containing a minor amount effective to reduce intake valve deposits of an ester compound formed from a polymethylol alcohol from the group consisting of tetramethylolmethane, and polymethylol derivatives of ethane, propane, and butane in which the derivative has at least three methylol groups, and an aliphatic hydrocarbon monocarboxylic acid from the group consisting of saturated aliphatic acids having substantially 14 to 24 carbon atoms and mixtures of substantially C14 to C24 aliphatic acids consisting of at least 50 percent of saturated acids, said ester compound having an average molecular weight ranging from about 825 to
 1500. 11. A method according to claim 10 in which said fuel composition contains from about 0.015 to 0.25 volume percent of said ester. 